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From the Divisions of Aging (J.A.D., T.K., J.E.B., J.M.G., G.L.) and Preventive Medicine (T.K., J.E.B., J.M.G.), Department of Medicine, Brigham and Women's Hospital, Harvard Medical School; Department of Epidemiology (T.K., J.E.B., G.L.), Harvard School of Public Health; Department of Ambulatory Care and Prevention (J.E.B.), Harvard Medical School; and Massachusetts Veterans Epidemiology Research and Information Center (J.M.G.), VA Boston Healthcare System, Boston, MA.
Address correspondence and reprint requests to Dr. Tobias Kurth, Brigham and Women's Hospital, Division of Aging, 1620 Tremont St., Boston, MA 02120-1613
Objective: To evaluate the association between Parkinson disease (PD) and mortality after adjustment for comorbidities.
Methods: We conducted a matched cohort analysis among 22,071 participants in the Physicians Health Study. Five hundred sixty incident PD cases were identified by self-report. We used a modified Charlson Comorbidity Index to calculate a comorbidity score. Each PD case was matched by age to a comparator who was alive and had an identical comorbidity score at the time of PD diagnosis of the case. Both cohorts were followed for all-cause mortality. We used proportional hazards models to calculate hazard ratios (HRs) for mortality.
Results: A total of 330 participants died over a median follow-up of 5.8 years, 200 (35.7%) in the PD group and 130 (23.2%) in the reference group. After adjustment for smoking and age at PD onset, the HR for mortality was 2.32 (95% CI 1.85–2.92). The mortality risk remained significant with increasing age at onset, even in those aged
80 years (HR = 2.10; 95% CI 1.44–3.00). The increased risk was apparent for short PD duration (<2 years) and remained stable with increasing duration. We found no different risk of mortality associated with PD according to smoking status.
Conclusions: In this large prospective cohort of men and after matching on comorbidities, we found that Parkinson disease patients had an increased risk of all-cause mortality. Mortality was increased regardless of disease duration, did not diminish with increasing age at onset, and was not influenced by smoking status.
GLOSSARY: BMI = body mass index; COPD = chronic obstructive pulmonary disease; HR = hazard ratio; ICD-9 = International Classification of Diseases, 9th Revision; PD = Parkinson disease; PHS = Physicians Health Study; RR = relative risk; WHO = World Health Organization.
tkurth{at}rics.bwh.harvard.edu
The Physicians Health Study is supported by grants CA 34944 and CA 40360 from the National Cancer Institute and grants HL-26490 and HL-34595 from the National Heart, Lung, and Blood Institute, Bethesda, MD.
Disclosure: The authors report no conflicts of interest relevant to this article. J.A.D. has nothing to disclose. T.K. has received investigator-initiated research funding as Principal or Co-Investigator from the National Institutes of Health, Bayer AG, McNeil Consumer & Specialty Pharmaceuticals, and Wyeth Consumer Healthcare; is a consultant to i3 Drug Safety; and has received an honorarium from Organon for contributing to an expert panel. J.E.B. has received investigator-initiated research funding and support as Principal Investigator from the National Institutes of Health (the National Heart, Lung, and Blood Institute, the National Cancer Institute, and the National Institute of Aging) and Dow Corning Corporation; research support for pills and/or packaging from Bayer Heath Care and the Natural Source Vitamin E Association; and honoraria from Bayer for speaking engagements. J.M.G. has received investigator-initiated research funding and support as Principal Investigator from the National Institutes of Health, BASF, DSM Pharmaceuticals, Wyeth Pharmaceuticals, McNeil Consumer Products, and Pliva; has received honoraria from Bayer and Pfizer for speaking engagements; and is a consultant for Bayer, McNeil Consumer Products, Wyeth Pharmaceuticals, Merck, Nutraquest, and GlaxoSmithKline. G.L. has received investigator-initiated research funding from the National Institutes of Health and has received honoraria from Pfizer and Lilly Pharmaceutical for speaking engagements in 2003.
Received May 30, 2007. Accepted in final form August 14, 2007.
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